Memory devices are typically provided as internal, semiconductor, integrated circuits in computers or other electronic devices. There are many different types of memory including volatile and non-volatile memory. Volatile memory can require power to maintain its data and includes random-access memory (RAM), dynamic random access memory (DRAM), and synchronous dynamic random access memory (SDRAM), among others. Non-volatile memory can provide persistent data by retaining stored information when not powered and can include NAND flash memory, NOR flash memory, read only memory (ROM), Electrically Erasable Programmable ROM (EEPROM), Erasable Programmable ROM (EPROM), and phase change random access memory (PCRAM), among others.
Memory devices can be combined together to form a solid state drive (SSD). A solid state drive can include non-volatile memory, e.g., NAND flash memory and NOR flash memory, and/or can include volatile memory, e.g., DRAM and SRAM, among various other types of non-volatile and volatile memory. Flash memory devices, including floating gate flash devices and charge trap flash (CTF) devices using semiconductor-oxide-nitride-oxide-semiconductor and metal-oxide-nitride-oxide-semiconductor capacitor structures that store information in charge traps in the nitride layer, may be utilized as non-volatile memory for a wide range of electronic applications. Flash memory devices typically use a one-transistor memory cell that allows for high memory densities, high reliability, and low power consumption.
An SSD can be used to replace hard disk drives as the main storage device for a computer, as the solid state drive can have advantages over hard drives in terms of performance, size, weight, ruggedness, operating temperature range, and power consumption. For example, SSDs can have superior performance when compared to magnetic disk drives due to their lack of moving parts, which may avoid seek time, latency, and other electro-mechanical delays associated with magnetic disk drives. SSD manufacturers can use non-volatile flash memory to create flash SSDs that may not use an internal battery supply, thus allowing the drive to be more versatile and compact.
An SSD can include a number of memory devices, e.g., a number of memory chips (as used herein, “a number of” something can refer to one or more of such things, e.g., a number of memory devices can refer to one or more memory devices). As one of ordinary skill in the art will appreciate, a memory chip can include a number of dies and/or logical units (LUNs). Each die can include a number of memory arrays and peripheral circuitry thereon. The memory arrays can include a number of memory cells organized into a number of physical pages, and the physical pages can be organized into a number of blocks.
SSDs can include a logical address (LA) table, such as a logical block address (LBA) table. An LBA table can be used to record the information that links the logical address of data to the physical location of the data in the memory arrays of an SSD. The LBA table can be stored in volatile memory in the solid state drive and a copy of the LBA table can also be stored in non-volatile memory in the solid state drive. The LBA table can be used to locate the physical location of data in the solid state drive to read the data when a read request is initiated in the solid state drive. A read request for data at a specific logical address can be initiated by a host. The logical address can be found in the LBA table and a corresponding physical address can then be indicated. The solid state drive can read the data from the indicated physical address to complete the read request for the solid state drive.
A solid state drive that does not have an LBA table with the current, e.g., most recent, information about relationships between the logical address and the physical address for the data in the solid state drive can make some data in the solid state drive inaccessible. Therefore, an LBA table that is current is desirable for complete access to all of the data in the solid state drive. An LBA table in the solid state drive can be lost or incomplete after a power interrupt due the LBA table being stored in volatile memory and/or the LBA table being periodically stored in non-volatile memory. Therefore, a power interrupt can cause a solid state drive to have an LBA table that does not have information about data that was written to the solid state drive in a time just prior to the power interrupt.